1. Field of the Invention
This invention relates to a stretch film comprising a resin composition prepared by blending an ethylenevinyl acetate copolymer resin and/or polybutadiene resin with specific additives. This film is particularly useful for wrapping fresh foods.
2. Description of the Prior Art
In recent years, the demand for improved films for wrapping fresh foods such as meat, fish, vegetables, fruits, etc., has increased with the expansion in the number of supermarkets using such wrapping films. Most of conventional stretch films for wrapping contain plasticized PVC (polyvinyl chloride) as a major component. These PVC films are often used for wrapping foods and, in many cases, they are applied directly to foods (in many cases being used to wrap cooked foods to be eaten directly from the package). The adverse influences of such use of PVC films (e.g., migration of residual monomer into the food) have been widely publicized. Also, the problem of generating hydrogen chloride gas upon incineration of waste PVC film is well known. Therefore, the use of PVC inherently involves difficult problems.
As a consequence of the foregoing problems, investigations have been made to develop stretch films capable of taking the place of aforesaid plasticized PVC film. Such films have comprised compositions containing mainly polyethylene, ethylene-vinyl acetate copolymer, polybutadiene or the like in order to try to overcome the above-described problems of sanitary food and environmental pollution. However, no film has yet been obtained that can sufficiently satisfy somewhat incompatible requirements for wrapping film, i.e., it must at the same time have (1) a sliding property and (2) a self adhesion property. More particularly, one requirement for wrapping film is to have a high self adhesion property necessary for superposing the film during or at the end of a wrapping step; another requirement that the film must possess is a smooth sliding property against rolls of a wrapping machine or against articles to be wrapped. It is technically very difficult to satisfy these two requirements at the same time. Poor self adhesion and poor sliding properties of aforesaid stretch films such as polyethylene film, ethylene-vinyl acetate copolymer film or polybutadiene film have rendered them less popular than PVC films, because these properties render them less suitable for wrapping machines than the plasticized PVC film.
In addition to the above-described two requirements, there are various other interrelated requirements such as: (3) that the range of suitable heat-sealing temperature be wide; (4) that the film be flexible and tough; (5) that the film be transparent, glossy, and fog-resistant.